First record of the deep-water shark Etmopterus spinax (Chondrichthyes: Etmopteridae) from the southern Baltic Sea (Pomeranian Bay)

Abstract

Summary: Etmopterus spinax is a deep-sea shark species that inhabits the northeast Atlantic and the western Mediterranean Sea. Skagerrak and Kattegat are reported to be part of the distribution of the species, but it has never been noted in the southern Baltic. Lacking any commercial value and commonly discarded in trawl and longline fisheries, E. spinax has been poorly studied. We reported on the first record of one specimen of E. spinax caught in the Pomeranian Bay on October 13, 2016 at a depth of 10 m. It was a female measuring 42.7 cm in total length. The morphological examination of the specimen was supported with COI barcode analysis, whereas species assignment to the population of origin was conducted based on a control region (CR) sequence of mtDNA. COI and CR sequence searches against GeneBank confirmed its identity as E. spinax and revealed that the specimen shared identical haplotypes with fish from populations in the Azores, Rockall Trough, and west of Ireland in the northeast Atlantic. The stomach contents, parasitic fauna, and hepatosomatic index of the individual were also examined. Only one L3 larval Anisakis simplex nematode specimen was collected from the stomach lumen of the shark. The specimen could have arrived in the Pomeranian Bay along with an inflow from the North Sea. In December 2014, a strong Major Baltic Inflow brought large amounts of water into the Baltic Sea, followed by some inflows of moderate intensity. Keywords: Etmopterus spinax, Anisakis simplex, Pomeranian Bay, Southern Baltic Sea, Inflow from the North Sea